PHP verification code image cannot be output solution_PHP tutorial

PHP verification code image cannot be output

File name global_func.php

Function _code(){

//Run verification code

//Number of random codes

$_rnd_code=4;

　for($i=0;$i<$_rnd_code;$i++){

　$_nmsg.=dechex(mt_rand(0, 15));

　}

//Save in session

　$_SESSION['code']=$_nmsg;

//Length and height

$_width=75;

$_height=25;

//Create a picture

$_img=imagecreatetruecolor($_width,$_height);

//White

　$_white=imagecolorallocate($_img, 255, 255, 255);

//Filling

Imagefill($_img, 0, 0, $_white);

　$_flag=false;

　if($_flag){

// Black, border

　$_black=imagecolorallocate($_img, 0,0,0);

Imagerectangle($_img, 0,0, $_width-1,$_height-1,$_black);

　}

//Draw 6 lines

for($i=0;$i<6;$i++){

$_rnd_color=imagecolorallocate($_img, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255));

Imageline($_img,mt_rand(0,$_width),mt_rand(0,$_height),mt_rand(0,$_width),mt_rand(0,$_height), $_rnd_color);

　}

//Snowflakes follow

for($i;$i<100;$i++){

$_rnd_color=imagecolorallocate($_img,mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));

Imagestring($_img,1, mt_rand(1, $_width),mt_rand(1,$_height), '*', $_rnd_color);

　}

//Output verification code

for($i=0;$i

$_rnd_color=imagecolorallocate($_img, mt_rand(0, 100), mt_rand(0, 150), mt_rand(0, 200));

Imagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10), mt_rand(1,$_height/2),$_SESSION['code'][$i],$_rnd_color );

　}

//Output image

header('Content-Type:image/png');

imagepng($_img);

//Destroy

imagedestroy($_img);

　}

If I call function _code(); in the global_func.php file, an error will appear and a red cross will appear.

code.php

　_code();

I can use this by writing it directly in code.php.

code.php

//Number of random codes

$_rnd_code=4;

　for($i=0;$i<$_rnd_code;$i++){

　$_nmsg.=dechex(mt_rand(0, 15));

　}

//Save in session

　$_SESSION['code']=$_nmsg;

//Length and height

$_width=75;

$_height=25;

//Create a picture

$_img=imagecreatetruecolor($_width,$_height);

//White

　$_white=imagecolorallocate($_img, 255, 255, 255);

//Filling

Imagefill($_img, 0, 0, $_white);

　$_flag=false;

　if($_flag){

// Black, border

　$_black=imagecolorallocate($_img, 0,0,0);

Imagerectangle($_img, 0,0, $_width-1,$_height-1,$_black);

　}

//Draw 6 lines

for($i=0;$i<6;$i++){

$_rnd_color=imagecolorallocate($_img, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255));

Imageline($_img,mt_rand(0,$_width),mt_rand(0,$_height),mt_rand(0,$_width),mt_rand(0,$_height), $_rnd_color);

　}

//Snowflakes follow

for($i;$i<100;$i++){

$_rnd_color=imagecolorallocate($_img,mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));

Imagestring($_img,1, mt_rand(1, $_width),mt_rand(1,$_height), '*', $_rnd_color);

　}

//Output verification code

for($i=0;$i

$_rnd_color=imagecolorallocate($_img, mt_rand(0, 100), mt_rand(0, 150), mt_rand(0, 200));

Imagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10), mt_rand(1,$_height/2),$_SESSION['code'][$i],$_rnd_color );

　}

//Output image

header('Content-Type:image/png');

imagepng($_img);

//Destroy

imagedestroy($_img);

I run this verification code directly without encapsulating it into a function. I can use the verification code and everything is fine.

But after I use function _code(), a red cross is displayed in the html after calling _code(). I don’t know why

　------Solution--------------------

Could it be the reason for header('Content-Type:image/png');?

The BOM header will affect the file type expected by the browser

　------Solution--------------------

Even if it is written as a function, there is no problem in calling it.

Function _code(){

//Run verification code

　}

　?>

Another page

include("./test/test.php");

　_code();

　------Solution--------------------

If you open the php error message, you will know why..